Correct spacing for zero-length progress bar

Dependencies

• [2] MXQ3U2DP Shorter progress bars
• [3] BNPSVXIC Friendlier progress bars
• [4] GNMZNKB4 Cursors cleanup

Change contents

• replacement in pijul/src/progress.rs at line 186
  [2.194]→[3.9280:9298](∅→∅),[3.9280]→[3.9280:9298](∅→∅)
  − {
  [2.194]

  [3.9298]
  + if *n == 0 {

  + nw -= 2

  + } else {